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[几何] 立几小题

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青青子衿 posted 2014-1-23 15:30 |Read mode
空间四边形ABCD中AB⊥CD,BC⊥AD,下列哪些命题是假命题:
①AB⊥平面BCD;②BC⊥平面BAD;③平面BAD⊥平面BCD;④AB⊥BD;⑤AD⊥CD

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其妙 posted 2014-1-23 17:00
回复 1# 青青子衿
对棱互垂?
正四面体就满足,你说那些是假命题呢?
original poster 青青子衿 posted 2014-1-23 18:30
回复 2# 其妙
对棱互垂?
正四面体就满足,你说那些是假命题呢?
对棱互垂怎么推出正四面体?? 谢谢!

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